The ISI (Infrared Stellar Interferometer), an interferometer operating at mid-infrared wavelengths will be discussed,
including both the instrumentation and results of stellar measurements. The ISI operates in the 10
micron wavelength region using three movable telescopes and heterodyne detection with CO<sub>2</sub> laser local oscillators.
Phase closure allows rather complete imaging of stars and their dust shells, including measurement of
asymmetries. Measurements have been conducted of the emission of material from stars, some ejected at very
high velocity, the size and change of size of some stars, stellar ellipticity, and stellar asymmetry. Material blown
off from stars is often emitted in periodic shells, and frequently asymmetric.